PCIe Multifunction Error Aggregation via Daisy Chain Logic
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Solution Overview
Problem
Multifunction PCIe devices face issues with error message flooding, which reduces link bandwidth due to limitations in the number of error messages that can be generated, necessitating a method to determine which functions should issue error messages during events.
Innovation Solution
A daisy chain approach is used to aggregate and manage error messages, allowing each function entity to decide whether to generate a blocking or pass-through control, thereby limiting the number of error messages and ensuring efficient bandwidth utilization without requiring dedicated logic blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If each function in a multifunction PCIe device generates error messages independently, then complete error reporting is achieved, but link bandwidth is reduced due to error message flooding
Solution Approach 1:
The patent merges error message generation from multiple functions into a single unified error message. When an error event occurs, the root complex generates one error message that contains error status bits for all functions, consolidating what would otherwise be multiple separate error messages into a single message that preserves complete error reporting information.
Solution Approach 2:
The error message structure is designed to be universal across all functions in the multifunction PCIe device. A single error message format can represent error states for multiple functions simultaneously, allowing the same message structure to serve all functions rather than requiring function-specific error messages.
2Loss of information
If multiple error messages are generated for the same error event, then detailed error information is provided, but the number of error messages exceeds specification limits
Solution Approach 1:
The patent combines multiple error information elements into a single error message by using error status bits that can represent different functions and error types within the same message structure, thereby providing detailed error information without increasing the number of messages.
Solution Approach 2:
The error message uses parameter encoding where error status bits can take different values to represent different error conditions and functions. This allows a single message to convey multiple pieces of error information through parameter variation rather than requiring multiple messages.
Data Source
AI summary
A method of aggregating events in a PCIe (Peripheral Component Interconnect Express) multifunction device minimizes reported error messages, where several functions share a common PCIe interface logic. A predetermined number of function entities with logical gates, connected in daisy chain configuration, process incoming information, and a decision is made whether each function entity will generate a blocking control or a pass-through control. The error messages are aggregated across the function entities in a single clock cycle with the help of an error controller. The functions can be from IEEE 1394 interface, graphics display controller, sound card, PCIe switch, or PCIe to PCI bridge connection. Each function preferably has a different configuration and security level setting for error reporting and messaging. There may be a plurality of parallel daisy chains, and the PCIe device may include three layers namely, a physical layer, data link layer and transaction protocol layer (for error logging, reporting).